Nickle base cast alloys are extensively used for turbine component design requiring corrosion resistance and high temperature strengths for use at temperatures as high as about 1800.degree. F. Three such closely related alloys manufactured by International Nickel Company, are designated inconel 713C, Inconel 713LC and IN 100, which have the following nominal chemical composition (weight percent):
______________________________________ Element 713C 713LC IN 100 ______________________________________ Chromium 12.5 12.0 10.0 Molybdenum 4.2 4.5 3.0 Carbon 0.12 0.05 0.18 Aluminum 6.1 5.9 5.5 Titanium 0.8 0.6 4.7 Columbium plus Tantalum 2.0 2.0 -- Zirconium 0.10 0.10 0.06 Cobalt -- -- 15.0 Boron 0.012 0.010 0.014 Nickel Balance Balance Balance ______________________________________
The poor weldability of such nickel base alloys results in frequent problems of base metal cracking during the welding process and subsequent high temperature brazing or heat treat cycles. It is believed that during welding, a low melting point constituent is formed at the grain boundaries which causes cracking in the base metal heat-affected zone because the heat generated during welding causes melting of this eutectic phase (constituent) which subsequently cracks at the grain boundaries during weld solidification. This chronic problem causes excessive and costly rework of welded components and prevents optimum design latitude for components requiring joining during fabrication.